Snap action switch with free-floating roller and cam shaped actuator

ABSTRACT

Principles of switching are disclosed which variously enable achievement of simplicity, high current for size, long life and automated production. The principles are applicable to most switching situations. Conductor elements which are discrete, loosely confined by casing, dropped into operating position during assembly, circular, rigid, rotatable, elongated, in the form of a laterally moving rod, serving as a snap action bus, and capable of double make and break are variously shown. Directing assemblies move the conductor elements along a first surface until a release region is reached. Resilient energy stored during that movement then propels the conductor element away from the first surface, against an opposed surface. Assemblies are shown which are movable and self adjustable so as to constrain the conductor element against either opposed surface. Directing assemblies featured have faces that constrain the conductor, wedge it forward and, after release, divert it to the opposed surface. Projecting members that define these faces are shown as actuators movable relative toward the contact surfaces. Resilient members are shown on the opposite side of the conductor element, confined between the latter and a formation of the housing. The resilient members are arranged to propel the conductor along a path lying at an acute angle to the path the conductor element followed earlier as it approached the release region.

United States Patent Burch et a1.

[15] 3,681,547 [451 Aug. 1, 1972 m1 SNAP ACTION swiTcH WITH FREE-FLOATING ROLLER AND cAM SHAPED ACTUATOR A 22 Filed: Nov. 19, 1969 [21]Appl. No.: 877,959

[52] US. Cl......' ..200/68, 200/77, 200/166 BB [51] Int. Cl. ..H0lh13/32, HOlh 13/28 [58] Field of Search ..200/68, 73, 166 B, 52, 6, 77

[56] References Cited UNITED STATES PATENTS 3,600,533 8/ 1971 English..200/68 2,447,318 8/1948 Dazley et al. ..200/77 X 2,633,510 3/1953Schellman ..200/68 2,945,098 7/1960 Ludwig ..200/166 B UX 3,274,3559/1966 Francy ..200/77 FOREIGN PATENTS OR APPLICATIONS 1,006,040 4/1957Germany ..200/68 841,864 5/1939 France ..200/159 1,210,942 3/ 1960France ..200/166 B 593,859 10/ 1947 Great Britain..' ..200/68 PrimaryExaminer-Robert K. Schaefer Assistant Examiner-Robert A. VanderhyeAttorney-Townsend M. Gunn 57 g a ABS RACTv Principles of switching aredisclosed which variously enable achievement of simplicity, high currentfor size, long life and automated production. The principles areapplicable to most switching situations.

Conductor elements which are discrete, loosely confined by easing,dropped into operating position during assembly, circular, rigid,rotatable, elongated, in the form of a laterally moving rod, serving asa snap action bus, and capable of double make and break are variouslyshown.

Directing assemblies move the conductor elements along a first surfaceuntil a release region is reached. Resilient energy stored during thatmovement then propels the conductor element away from the first surface,against an opposed surface. Assemblies are shown which are movable andself adjustable so as to constrain the conductor element against eitheropposed surface. Directing assemblies featured have faces that constrainthe conductor, wedge it forward and, after release, divert it to theopposed surface. Projecting members that define these faces are shown asactuators movable relative toward the contact surfaces. Resilientmembers are shown on the opposite side of the conductor element,confined between the latter and a formation of the housing. Theresilient members are arranged to propel the conductor along a pathlyingat an acute angle to the path the conductor element followed earlier asit approached the release region.

3 Claims, 27 Drawing Figures PATENTEDAHB' H912 SHEET 1 [IF 5 PATENTEDAus1 1912 3.681. 547

SHEET UF 5 2 FIG I20 FIG /2b PATENTEDAUS 1 m2 SHEET 5 [1F 5 FIG /50 SNAPACTION SWITCH WITH FREE-FLOATING ROLLER AND CAM SHAPED ACTUATOR Thisinvention relates to switches and their manufacture.

It is the object of the invention to provide principles which may beemployed for reducing the number of parts of a switch and theircomplexity, for enabling mass production of the parts and theirautomated assembly, for obtaining improved snap action characteristicssuch as improved life and greater switching capacity, and for performinga wide variety of switching function with the same parts.

In one important aspect the invention features a discrete conductorelement, e.g., a rod or a free-floating bar or cylinder, which isconstrained to move relative to a contact surface while a resilientmember, e.g. a compression spring, is stressed. When a release region isreached the conductor element is urged to move through space, away fromthe contact surface at an angle to its earlier path. According to oneimportant aspect of the invention a snap action switch is achieved inwhich the snap acting conductor element forms a bridging current pathbetween a pair of electrical contacts, the snap acting bridging elementcomprising a smooth surface of revolution in the region where a biasingmeans directly engages it, the biasing means applying radial forcewithout restraint against lateral relative movement. I

These and other objects and features of the invention will be understoodfrom the abstract and claims and the following description of preferredembodiments with reference to the drawings wherein:

FIG. 1 is a perspective view of the arrangement of contacts anddiscrete, rod-form conductor element of a specific embodiment of theinvention while FIGS. 2 and 2a are endand top views of the operatingportions of that embodiment;

FIG. 3 is a diagrammatic representation of a general embodiment of theinvention;

FIGS. 3a, 3b, and 3c are views similar to FIG. 3 showing the switch atvarious points during its operation while FIG. 3d is a magnified view ofthe actuator of FIG. 3; and FIG. 3e is a vector representation of thelengths of the spring of the embodiment of FIG. 3 occurring in thevarious FIGS. 3, 3a and 3b;

FIG. 4 is a vertical cross-section of a third embodiment according tothe invention while FIG. 5 is a crosssection of that embodiment alonglines 5-5;

FIG. 6 is a diagrammatic representation of another embodiment while FIG.6a is a view similar to FIG. 6 showing the elements in a differentposition during switch operation;

FIG. 7 is a diagrammatic view of another embodiment in which a springand directing surface for the conductor element are formed as anextension of a holder for that element;

FIGS. 8 and 80 show another embodiment employing a tilting surface forreleasing the conductor element;

FIG. 9 shows a switch construction in which movable contacts roll a freeconductor element through the release region;

FIGS. 10 and 11 are side and end diagrammatic views of anotherembodiment of the invention employing a conductor element of rod form;

FIGS. 12, 12a and 12b, show diagrammatically an actuator movingtransversely relative to a stationary contact;

FIGS. 13 and 14 are similar cross-sections but on different scale ofanother embodiment of the invention;

FIG. 15 is a cross-section of still another embodiment of the inventionwhile FIG. 15a is a view similar to FIG. 15 with the parts in anotherposition and FIG. 16 is an exploded view thereof. I

The embodiment of FIGS. l-2 comprises a conductor element 1 in the formof an elongated cylinder bar of rigid conductive material. It spansbetween two stationary members 2, 2a, which together form a pair offirst contacts, having terminals t. Two other members 3, 3a, are opposedto members 2, 2a, forming a second pair of contacts. The pairs ofcontacts are spaced apart a distance s greater than the thickness ofconductor element 1, and the length E of the conductor element isgreater than the spacing p between members of the contact pairs.

Referring to FIGS. 2 and 2a a directing assembly is formed by actuator 4on one side of conductor element 1 and spring 5 on the other side. Theconductor element 1 is thus not carried by any other member but israther resiliently constrained against the contact 2 by three-pointslidable engagement of parts upon its periphery.

With two leads completing a circuit connected to terminals t and t thecurrent flows through the bar 1 of rigid material. When the actuator 4moves down, the bar moves, usually rolling but sliding also permitted,relative to the two stationary contact members, 2, 2a. Transverserelative motion of the'bar also occurs with reference. to axis A ofactuator 4. When the release point R formed by the actuator is reached,the bar moves abruptly from the two contact members 2 and 2a, across thespace 3 and into engagement with'contact members 3 and 3a. This actionconstitutes a double break of the circuit through terminals t,, anddouble make between t;, and t with the inherent advantage of addedcapacity that this gives. Also to be noted are the facts that current iscarried only through rigid members, and that relative movement of theconductor element with the engaged contacts occurs up to the very pointof snap action.

The snap action will be better understood in light of discussion of themore general embodiment of FIG. 3. There a conductor element 10 of rigidmaterial and circular form is adapted to move in the direction of arrowa along the surface of stationary contact 12 as seen in the perspectiveview of FIG. 1 the conductor bridges a spaced pair of members. Theconductor element 10 is constrained against this contact by a spring 14and an actuator 16, these engaging conductor 10 on opposite sides on aline making an angle a of e.g. 45 to the surface of stationary contact12. The actuator moves straight along this line, axis A, and the springis arranged to be compressed in the direction of this line. Theuncompressed length L of spring 14 is shown in FIG. 3e.

The conductor 10 is free to move with respect to each member. While itmoves in direction a rolling along the second contact 12 it also rotatesrelative to spring 14 and actuator 16 as well as moving laterallyrelative to axis A.

r The actuator face16a which engages conductor 10, is set at an obtuseangle b (e.g., 110, FIG. 3d) to the direction of movement of theactuator and this face 16a has an end release point R. Face 16a andcontact 12 thus form an acute angle crotch in which conductor 10 residesin stable position. Referring to FIG. 3, it engagescontact 12 at point xand actuator face 16a at point i, the latter. point being spaced fromrelease point R." In FIG. 3 the springis compressed to length L,. In FIG'. 3a actuator 16 has moved along its axis closer to I contact 12.Conductor 10 has travelled along contact L,, to pointy, spring 14 hascompressed to length 'La (La L, see FIG. 3e) and conductor 10 has movedtransversely relative to actuator 16 so that it is passing the'releasepoint R. This is an unstable position; When the centerof conductor 10passesa line projected 3 between release point R and mount l4rn of thefar end of thespring, then face 16a is no longer effective to constrainconductor 10 against contact 12. The conductor 10 is released and movesabruptly away from contact 12 under the influence of stored energy ofthe spring, which expands. v

Referring to FIGS. 3b and3c the actuator '16 is provided witha secondface 16b extending from release point R at an obtuse angle c (e.g. 110)to actuator axis A, in the opposite direction from face 16a. Thus faces16a and 16b define an included angle d less than 180, e.g., 140, havinga projecting'point at R. The angle of. face 16b provides a relief spacein'to'which the conductor" was urged. During expansion of the spring 14conductor escapes from release pointR along path a,, at an acute angleto earlier path a. Face l6b may be engaged by the conductor 10 during"this movement, and after conductor 10. has moved away from secondcontact 12 it engages face l6bat point e.

Referring to FIG. 3e it will be seen that the assembly has "acted tocompress" the spring 14 to a minimum length at the point where conductor10 reachesa position of release or instability, from which the conductormoves with expansion of the spring. Once the position of instability isreached (FlG.'3a) no further movement of the actuator is theoreticallyneeded to cause the abrupt'i'novement to the position depicted at FIG.3b. j 6 Second contact 18 extends parallel to contact 12, spaced fromit-a distance greater than D, the diameter of conductor l0.This secondcontact is shown being engaged by conductor while the latter engages theactuator'at point e. It is seen that conductor 10 is again constrainedand expansion of spring 14 is limited to length L5. The directingassembly has thus been self adjustable, effective to'constrain theconductor against eitherv of the opposed surfaces of contacts 12 and 10.

Upon return movement of the actuator (in the directionopposite of arrowA in FIG. 1) conductor 10 moves upwardly along contact ,18 while movingrelatively along facel6b of. actuator 16 from point e toward point R,fwhere face 16b ends. With conductor 10 still engaging contact 18, asthe center of conductor 10 passes the line projected between springmount 14,, and release point R, an unstable condition is again reached.Conductor l0 springs into the open space beyond point R, travellinglaterally along actua tor face 160 until it reaches contact 12, in thedotted line position shown in FIG.v 3c, spring length L A releasemovement of the actuator.

It is quite conceivable that the action here described with reference toFIGS. 3 and 30 'would be useful without an opposed contact, with-otherform of retaining member acting to hold the conductor. Another form ofreturn is also conceivable if return is required. A zig-zag path betweensuccessive contacts in a multiple action switch, progressing generallyin the same direction would eliminate return in certain switches. Herethe last contact for'instance could complete the loop with the firstcontact. In important instances, however, return movement as illustratedin FIGS. 3b and 3c is desired. Then the path of the conductor element isa closed'loop," between the-two pairs of contacts. With the particulararrangementshownit will be seen that this loop is in the form of aparallelogram. I

This general embodiment can be employed in numerous ways to accomplishswitching. For instance either the actuator 16 of the spring 14 could beconnected to a terminal to create a'circuit through conductor 10 to theengaged contact 12 or, 18, or even flexible pigtail connections to theconductor 10 could be employed. The advantage of all current carryingelements being of rigid material (hence thick and of high capacity) is.obtainedwhen the conductorserves as a shunt this could be accomplishedwith a track formed by two spaced members, along which the ball rolls. I6 In the preferred embodiment of FIGS. 4 and 5, the conductor .10. is arod audit is loosely disposed in the casing, spanning pairs of contacts,and confined against end-wise movement by walls of the casing. I

Here the switch comprises a casing e'.g of plastic into which are moldedfour rigid contact members,

formed surfaces of which define contacts 62, 63, 64 and 65,and'projecting ends of which defineterminal 67, 68, 69 and another notshown. (Toestablish a common terminal for instance contacts 62 and 64may be formed integrally in thesame rigid conductive member,

and connected to a common terminal.) In-the base of casing 60 a holeformation 70 is provided having a bottom surface. Into this hole isinserted a resilient member, here, coil spring 76. The parts areconstructed to permit reciprocatorymotion with contraction and expansionof the spring. A rigid bar 78 of -a length slightly less'than the insidedimension Li of casing 60 is droppedinto this construction, rests oncontacts 64 and and against the surface of the resilient member found atthe bottom endof the space between the opposed contact pairs. Conductor78 is shown engaging the spring directly, as is also truein certainfollowing -embodiments.

An actuator 82 is inserted in hole 84 in the cover 62 and the cover isthen secured to the base of casing .60 completing the switch. Reciprocalplungerinovernent of the actuator 82 is effective to cause the conductor78 to roll, mutually engaging, alternately, pairs of con-.

tacts 62, 63 and 64, 65.

The spring 76 is effective to cause return movement. of the plungeracting through thefconductor 78, as well a dropped into its hole and isconfined against the housing by the conductor which, is then dropped in.An operative switch is obtained by supplying the last part, theactuator, and affixing the coverwithout post assembly adjustments. Theseassembly operations can be performed entirely automatically, withoutneed of 1 skilled labor.

Initial work employing the invention resulted in the preferredembodiments just described and other embodiments of certain features, tobe described now referring to FIGS. 6-11. Other presently preferredembodiments will then be described in connection with FIGS. 13-16. Thereader will understand, however, that all of these embodiments are theresult of only a limited period of work, and with more time, and whendifferent switching requirements, size requirements, etc., areexamined,numerous other embodiments of features of the invention are expected tooccur to those skilled in the art.

Referring to FIG. 6, this embodiment is similar to FIG. 3b except thatthe actuator face 160 engaging conductor is at right angles to actuatoraxis A and a member having faces like those of the actuator in FIG. 3 issupported on the end of spring 14 and defines the constraining faces 20aand 20b with release point R. Movement of the actuator 16' in thedirection of the arrow causes conductor 10 to roll down contact 12 untilit reaches point R. There the contact is released and under the combinedeffect of the relieved face 20b and spring 14 conductor 10 escapes fromcontact 12 and is directed into a crotch formed by contact 18 andactuator surface 160. From this position, reverse movement can occursimilarly to that as described in connection with FIG. 30.

Referring to the embodiment of FIG. 7 an extension of common terminal 50has a cutout 52 which confines one end of the conductor rod. Where thisconfinement is a loose hole holding the rod, swivel movement of the rodwould occur with actuation. Snap action would occur at one end of therod only. On the other hand the shaping and spacing of the confinementsurfaces could be identical to the shape of the space between thecontacts and snap action would occur as previously described, withtransverse motion bodily of the rod.

A further cantilever spring extension 106 of common terminal 50 extendsunder conductor 10. The end 100 of this extension forms an angularmember for constraining the conductor 10 in the manner of member 20 ofFIG. 6.

Referring to the embodiment of FIG. 8, the conductor and springarrangement is the same as FIG. 3 but the actuator has a tiltablesurface 26 pivoted at 27 to the actuator rod 28. The rod moves in astraight line along axis A. As shown in FIG. 8 the surface 26 is tiltedto form an acute angle crotch K with contact 12, into which crotchconductor 10 is pressed by compression spring 14. A stop 29 preventsfurther counterclockwise rotation of tilt surface 26. As the actuatormoves downwardly unstable position or release region is reached when thecenter of conductor 10 reaches the point coinciding with a lineprojected between the spring mount 14m and pivot 27. Thereupon tiltsurface 26 turns clockwise, conductor 10 is released and moves abruptlyto contact 18, see FIG. 8a.

Referringto FIG. 9 a conductor 10 is constrained against contact 42 bystationary surface 46 and compression spring 44. Stationary surface 46defines faces 46a and 46b similar to the faces of the actuator of FIG.3. Contact 42 is movable by an actuator 52 transversely to the line Yprojected from spring mounting point 44m to release point R. Whencontact 42 moves to the left the conductor 10 rolls upwardly againstcontact 42. When the conductor reaches a point corresponding with theline Y, it is released and moves abruptly from contact 42 with expansionof spring 44. Here again, the conductor 10 reaches the release region,defined by the point R, still in electrical continuity with the contact42 with which it started, and a torque or relative rotation occurscontinually between the two to break incipient welds. Reaching point Rconductor 10 can then jump to opposite contact 48. Contact 48 is linkedto contact 42 by bridge 58 which includes insulating material 60, andthe entire assembly is moved by actuator 52. As with the otherembodiments, electrical connections can be made with terminal members byflexible pigtails connected to the various contacts.

In the embodiment of FIGS. 10 and 11 the rod 80 is formed integrallywith a leg 82 which incorporates a spring loop 84 in the nature of asafety pin. The remote end of this leg is captured loosely in an opening86 in the base of the switch. Movement of the actuator 90 downwardlyagainst the bar 80, causing the bar to travel in the direction t alongstationary contact 12, is

I effective to stress the spring. When the conductor 80 reaches releasepoint R of the actuator the conductor springs away in the mannerheretofore described. In place of actuator'90 a toggle type actuator,see e.g., FIG. 8, may be employed.

Referring first to the diagram of FIG. 12, an actuator 36 is shownmoving transversely relative to the stationary contact 32, in a straightpath A. The conductor 10 is forced by spring 34 into an acute anglecrotch k formed between contact 32 and face 36a of the actuator. As theactuator moves in the direction of the arrow A, a point of release R isreached (FIG. 12a) and the conductor 10 moves abruptly from surface 32,guided by face 36b which permits expansion of the spring as theconductor 10. moves away from contact 32.

Referring to FIGS. 13 and 14 the motion just described is incorporatedin a toggle switch in which the toggle member 140 is held in either ofits stable positions by the same spring 144 that serves to constrain theconductor member 150 and cause its snap movement. Contacts 112,113 areintegral with terminals t.

Referring to FIGS. 15, 15a and 16, the actuator of this embodiment isconstrained for straight line movement at a right angle to opposed pairsof contact surfaces 102, 103 and 106, 107. This is achieved simply by ahollow bore in the molded casing.

At the bottom of the space between the pairs of contacts a hole 112 isformed, into which is dropped spring 114. Conductor element 116, havingend retaining flanges 118 is dropped into the assembly, resting uponspring 1 l4.

The actuator 100 has a formed portion 101 presenting two faces 101a andl01b analagous to surfaces 36a and 36b of FIG. 2. The actuator isinserted into bore 110, with portion 101 lining up with the spacebetween the contacts, with face llb engaging the conductor 116,and'constraining the latter against contact 102. A spring ll 8 isinserted into bore 110 preceding the actuator, andseats in hole 120beyond the contacts. In th'n position retainer l22 isffixed in position,engaging flange 124 of the actuator, to hold theparts in operatingrelation.

- ,With further plunger'movement of actuator 100, while spring 1 18 iscompressed, the release pointpasses over the conductor 116 and thelatter is snapped against; contact 106 in the manner previouslydescribed. Upon release of actuating force F, spring I "118 returns theactuator to its original position, and

conductor 116 to contact 102.

, To achieve a push pull switch or relay the spring 118 may be omittedand the switch will remain in either position until a push or pullactuating force is applied.

These and numerous other embodiments will occur to those skilled in theart.

what is claimed is: r

l. A snap action switch having a bridging bar of electrically conductivematerial, the bar having a circular crosssection taken perpendicular tothe longitudinal defining opposed push surfaces and adapted to push saidbar back and forth, said cam being incorporated in stationary structureengaged by said bar during said movement, said push surfaces beingadapted to move in unison and being spaced'apart a distance greater thanthe. diameter of said bar, enablingone push surface to push said bar asit moves over said cam until the bar reaches an over-center positionwhereupon said bar 1 may snap over-center while free of said: pushsurfaces, the bar thenmoving intoraposition'to be engaged by said otherpush surface for return movement.

2. A snap action switch having a bridging bar of electrically conductivematerial, the bar having a circular cross-section taken perpendicular tothe longitudinal axis, a pair of electrical contacts across which saidbar bridges to complete a circuit, and a snap action assembly includinga cam and spring'for snapping said bar toward or away from saidelectrical contacts,said bar being free floating and said snap actionassembly comprising a resilient surface pressing against one side ofsaid bar, urging the opposite side-of. said bar against said cam, saidbar being free to move across and change its positionon said resilientsurface during said snap action, said switch including an actuator and asingle spring provides the resiliency for said resilient surface and isarranged to apply return forces to said actuator, whereby upon releaseof actuating forces said actuator returns to'its initial position.

3. The snap action switch according to claim 2 wherein said springcomprises a coil spring and said actuator comprises a plunger having acam-shaped end surface and a straight line of travel generally parallelto and toward the axis 2f said spring. I

1. A snap action switch having a bridging bar of electrically conductivematerial, the bar having a circular cross-section taken perpendicular tothe longitudinal axis, a pair of electrical contacts across which saidbar bridges to complete a circuit, and a snap action assembly includinga cam and spring for snapping said bar toward or away frOm saidelectrical contacts, said bar being free floating and said snap actionassembly comprising a resilient surface pressing against one side ofsaid bar, urging the opposite side of said bar against said cam, saidbar being free to move across and change its position on said resilientsurface during said snap action, said switch including a moving devicedefining opposed push surfaces and adapted to push said bar back andforth, said cam being incorporated in stationary structure engaged bysaid bar during said movement, said push surfaces being adapted to movein unison and being spaced apart a distance greater than the diameter ofsaid bar, enabling one push surface to push said bar as it moves oversaid cam until the bar reaches an over-center position whereupon saidbar may snap over-center while free of said push surfaces, the bar thenmoving into a position to be engaged by said other push surface forreturn movement.
 2. A snap action switch having a bridging bar ofelectrically conductive material, the bar having a circularcross-section taken perpendicular to the longitudinal axis, a pair ofelectrical contacts across which said bar bridges to complete a circuit,and a snap action assembly including a cam and spring for snapping saidbar toward or away from said electrical contacts, said bar being freefloating and said snap action assembly comprising a resilient surfacepressing against one side of said bar, urging the opposite side of saidbar against said cam, said bar being free to move across and change itsposition on said resilient surface during said snap action, said switchincluding an actuator and a single spring provides the resiliency forsaid resilient surface and is arranged to apply return forces to saidactuator, whereby upon release of actuating forces said actuator returnsto its initial position.
 3. The snap action switch according to claim 2wherein said spring comprises a coil spring and said actuator comprisesa plunger having a cam-shaped end surface and a straight line of travelgenerally parallel to and toward the axis of said spring.